<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>

        while (true) {
            let uname = prompt('请输入你的用户名')
            let password = +prompt('请输入你的密码')
            if (uname === 'admin' && password === 123456) {
                alert('登陆成功')
                break
            }else{
                alert('请重新输入用户名和密码')
            }
        }
    </script>

</body>

</html>